Commit de33c442 authored by Committed by Ingo Molnar
x86 PAT: fix performance drop for glx, use UC minus for ioremap(),...
x86 PAT: fix performance drop for glx, use UC minus for ioremap(), ioremap_nocache() and pci_mmap_page_range() Use UC_MINUS for ioremap(), ioremap_nocache() instead of strong UC. Once all the X drivers move to ioremap_wc(), we can go back to strong UC semantics for ioremap() and ioremap_nocache(). To avoid attribute aliasing issues, pci_mmap_page_range() will also use UC_MINUS for default non write-combining mapping request. Next steps: a) change all the video drivers using ioremap() or ioremap_nocache() and adding WC MTTR using mttr_add() to ioremap_wc() b) for strict usage, we can go back to strong uc semantics for ioremap() and ioremap_nocache() after some grace period for completing step-a. c) user level X server needs to use the appropriate method for setting up WC mapping (like using resourceX_wc sysfs file instead of adding MTRR for WC and using /dev/mem or resourceX under /sys) Signed-off-by: Suresh Siddha <firstname.lastname@example.org> Signed-off-by: Venkatesh Pallipadi <email@example.com> Signed-off-by: Ingo Molnar <firstname.lastname@example.org> Signed-off-by: Thomas Gleixner <email@example.com>
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